Treatment of acrylic ester polymers



polymers are those Patented'Dec. 3, 1946 TREATIWENT OF ACRYLIC ESTERPOLYMERS Stephen T. The B. F.

Semegen, Akron. Goodrich Company, New

Ohio, assignor to York, N. Y.,

a corporation of New York No Drawing. Application May 9, 1945, SerialNo. 592,923

20 Claims. (01. 260-837 This invention relates to a method for curingacrylic ester polymers and pertains more specifically to, a method fortransforming such polymers from soft, plastic materials to tough,resilient products similar to vulcanized rubber.

I have found that such transformation may be accomplished by dispersingin the polymer a small amount of an alkali metal salt of and heating theresulting composition. Among the silicates which may be employed arecrystalline hydrated sodium metasilicate, sodium disliciate, waterglass, potassium metasilicate, p0

, Of methyl acrylate. The esters themselves may silica tassiumdisilicate, lithium metasilicate, and the like. The hydrated alkalimetal silicates are par-. ticularly useful. The amount of silicateemployed is not critical, butmay vary over a wide range from about 2 toabout 25% by weight'of the polymer, although it is generally preferredto use'from about 5 to about 20% by weigh The silicate may bedispersed'in the polymer composition by any of the usual methods; forexample, by mixing it with the solid plastic polymeron a roll mill, orby adding the silicate in finely divided form to a solution of thepolymer in a suitable organic solvent. The silicate may also be mixedwith thepolymer by adding it either as a solid or in the form ofanaqueous solution or polymerizable be prepared in a conventionalmannerby reacting the appropriate alcohol with acrylic acid or acrylic acidchloride under esterification conditions, or by other known methods. Thepolymer need not be made solely-from an ester of acrylic acid, but maybe a plastic polymer made by the polymerization of a substantialproportion of an ester of acrylic acid with another materialcotherewith, such as, for example, vinyl halide, vinyl esters,vinylidene halide, and other ethylenic compounds.

- As an example of'the process of this invention, a plastic polymer ofmethyl acrylate was mixed on a roll mill with 10% by weight ofcrystalline hydrated sodium metasili'cate; the mixture was heated inamold about 60 minutes at a temperature of 275 to 320 F. The product nolonger posdispersion to an aqueous dispersion of the acrylic esterpolymer. I

The polymers to which my new process may be applied include any plasticor fusible polymers made by the polymerization of an ester of acrylicacid. Although some esters ofacrylic acid, for example, allyl acrylateor ethylene glycol diacrylate, may be polymerized 'to give a hard,brittle material having a very high melting point,

- it is also possible to obtain plastic or fusible polymers from suchesters; these plastic polymers may be treated by the process of myinvention in order to toughen them; The process of this invention is ofgreatest importance, however, when applied to plasticpolymers made bythe polymerization of estersof acrylic acid with saturated aliphaticmonohydric alcohols. Among such made by the polymerization of 2--chlorethyl acrylate, beta-diethylaminoethyl acrylate, 2-methoxyethylacrylate, 2-ethoxyethyl acrylate, 2- butoxy'ethyl acrylate, and thelike. Particularly important are polymers Y made by .the polymerizationof alkylesters of acrylic acid,

such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isobutylacrylate, n-amyl acrylate, lauryl acrylate, and the like. All of theforegoing esters of acrylic acid may be polymerizedby the methodscommonly employed for polymerization sessed the plastic properties ofthe original polymet, 'but on the contrary, resembled a strong,well-vulcanized soft rubber. Similar results may be obtained with otherpolymeric acrylic esters.

Any of the usual pigments and fillers commonly used in the rubber andplastics industries may be added to the composition without any delete-'rious effect upon the vulcanization process. Softeners, plasticizers,and other ingredients may also be employed if so desired.

The time and temperature at which the composition need be heated inorder to bring about the desired change, in properties varies with theparticular polymer employed, as well as with the kind and amount Ofsilicate in the composition. Although the process may be carried out byheating the composition for a very long time at temperaturesbelow 200F., for practical purposes it is generally necessary to employ atemperature between about 200 F. and 400 F., preferably between 250 andabout 325 I. At these temperatures the time required to obtain thedesired results varies between about 15 minutes and two hours, dependingupon the particular temperature and polymer employed.

' The product adheres strongly to many materials such as Wood andtextile fabrics, and can thereforebe used in the manufacture ofcomposite products, such as are made from rubber,

andi'n cases in which it does not adhere directly, it can be. secured-toother materials by means of flooring, and others.

This application is a continuation-in-part of my copending application,Serial No. 453,027, filed July 31, 1942.

Although I have herein disclosed specific embodiments of my invention, Ido not intend to limit myself solely thereto, but to include all of theobvious variations and modifications falling within the spirit and scopeof the appended claims.

I claim:

1. The process of curing a plastic polymer of an ester of acrylic acid,which comprises heating said polymer with from about 2 to about 25% byweight of an alkali metal salt of silica dispersed therein.

2. The process of curing aplastic polymer of a saturated aliphaticmonohydric alcohol ester of acrylic acid, which comprises heating saidpolymer with from about 2 to about 25% by weight of an alkali metal saltof silicadispersed therein.

3. The process of curing a plastic polymer of a saturated aliphaticmonohydric alcohol ester of acrylic acid, which comprises heating saidpolymer with. from about 2 to about 25% by weight of sodium silicatedispersed therein.

4. The process of curing a plastic polymer of an alkyl ester of acrylicacid, which comprises heating said polymer with from about 2 to about25% by weight of an alkali metal salt of silica dispersed therein.

5. The process of curing a plastic polymer of an alkyl ester of acrylicacid, which comprises heating said polymer with from about 2'to about25% by weight of sodium silicate dispersed therein.

6. The process of curing a plastic polymer of ethyl acrylate whichcomprises heating said polymer with from about 2 to about 25% by weightof an alkali metal salt of silica dispersed therein.

7. The process of curing a plastic polymer of ethyl acrylate, whichcomprises heating said polymer with from about 2 to about 25% by weightof sodium silicate dispersed therein.

8. The process of curing a plastic polymer of a saturated aliphaticmonohydric alcohol ester of acrylic acid, which comprises heating saidpolymer at about 250 to 325 F. with from about 2 to about 25% by weightof a hydrated alkali metal salt of silica dispersed therein.

9. The process of curing a plastic polymer of an alkyl ester of acrylicacid, which comprises heating said polymer at about 250 to about 325 F.,with from about 2 to about 25% by weight of a hydrated alkali metal saltoi silica dispersed therein.

10. The process of curing a plastic polymer of an alkyl ester of acrylicacid, which comprises heating said polymer at about 250 to about 325 F.with from about 2 to about 25% by weight of hydrated sodium silicatedispersed therein.

11. A cured polymer composition made by heating a plastic polymer of anester of acrylic acid with from about 2 to about 25% by weight of analkali metal salt .of silica dispersed therein.

12. A cured polymer composition made by heating a plastic polymer of asaturated aliphatic monohydric alcohol ester of acrylic acid with fromabout 2 to about 25% by weight of an alkali metal salt of silicadispersed therein.

13. A cured polymer composition made by heating a plastic polymer of asaturated aliphatic monohydric alcohol ester of acrylic acid with fromabout 2 to about 25% by weight of sodium silicate dispersed therein.

14. A cured polymer composition made by heating a plastic polymer of analkyl ester of acrylic acid with from about 2 to about 25% by weight ofan alkali metal salt of silica dispersed therein.

15. A cured polymer composition made by heating a plastic polymer of analkyl ester of acrylic acid with from about 2 to about 25% by weight ofsodium silicate dispersed therein.

16. A cured polymer composition made by heating a plastic polymer ofethyl acrylate with from about 2 to about 25% by weight of an alkalimetal salt of silica dispersed therein.

17. A cured polymer composition made by heating a plastic polymer ofethyl acrylate with from about 2 to'about 25% by weight of sodiumsilicate dispersed therein.

18. A cured polymer composition made by heating a plastic polymer of asaturated aliphatic monohydric alcohol ester of acrylic acid at about250 to about 325 F. with from about 2 to about 25% by weight of ahydrated alkali metal salt of silica dispersed therein.

19. A cured polymer composition made by heating a plasticpolymer of analkyl ester of acrylic acid at about 250 to about 325 F, with from about2 to about 25% by weight of a hydrated alkali metal salt of silicadispersed therein.

20. A cured polymer composition made by heating a plastic polymer 01' analkyl ester of acrylic acid at about 250 to about 325 F. with from about2 to about 25% by weightof hydrated sodium silicate dispersed therein.

STEPHEN T. SEMEGEN.

